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The efficacy of photon-initiated photoacoustic streaming and sonic activated irrigation combined with QMiX solution or sodium hypochlorite against intracanal biofilm

The aim of the study was to assess the antibacterial efficacy of photon-initiated photoacoustic streaming (PIPS) using an Er:YAG laser and sonic activated irrigation combined with QMiX irrigant or sodium hypochlorite against Enterococcus faecalis intracanal biofilm. Root canals of 91 human extracted teeth with single straight canal were instrumented, sterilized in plasma, contaminated with Enterococcus faecalis and incubated at 37°C for 15 days. The infected teeth were then randomly distributed into six experimental groups: G1: PIPS/Er:YAG laser (wavelength: 2940 nm, pulse energy: 20 mJ, 15 Hz, pulse duration: 50 μs, 3x20 s) with the QMiX irrigant ; G2: PIPS/Er:YAG laser activated 2.5% NaOCl ; G3: sonic activated irrigation (EndoActivator system) for 60 s with the QMiX irrigant ; G4: sonic activated irrigation for 60 s with 2.5% NaOCl ; G5: 30-gauge needle irrigation with the QMiX irrigant ; G6: 30-gauge needle irrigation with 2.5% NaOCl. The positive control group was rinsed with sterile saline solution. The root canals were sampled by flushing with saline solution at baseline and after the treatments, serially diluted and cultured. The number of bacteria in each canal was determined by plate count. The presence and the absence of Enterococcus faecalis in root canals were also demonstrated by polymerase chain reaction (PCR) and the pattern of the bacteria colonization after 15 days was visualized by scanning electron microscopy. The results were analysed by the Wilcoxon test (intragroup analysis) and the Mann-Whitney U test (intergroup analysis). There was significant reduction in the bacterial population for all groups (p<0.001). The best antibacterial efficacy was recorded after sonic activated irrigation with both NaOCl (99.97%) and QMiX (99.99%) and after PIPS with QMiX (99.97%), which were more effective than conventional irrigation with NaOCl (88%) and the PIPS with the NaOCl (97%). Also, the PIPS with QMiX solution provided the highest number of sterile samples (five). There were no difference in the bacteria reduction between the active irrigation techniques, regardless of the irrigant used. Although the laser activation did not improve the antimicrobial action of the NaOCl nor QMiX, the fact that it generated the greatest number of sterile samples warrants further investigation.

laser-activated irrigation; PIPS; Enterococcus faecalis; sonic irrigation

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